Figure 3.

Summary of results of experiments where antibodies to various G-protein α subunits were added to the pipette solution. mIcat was measured in the same way as shown in Figure 2, and its amplitude was plotted against the carbachol concentration on a logarithmic scale. Control data (n=53) are shown in (a) and as a dotted line in (b–d) for comparison. (a) Gα_i3/Gα_o antibodies (Calbiochem, n=9; NEN™, n=10) and Gα_o antibodies (Calbiochem, n=7); (b) Gα_i1/Gα_i2 antibodies (Calbiochem, n=6; NEN™, n=10); (c) Gα_i1 antibodies (Calbiochem, n=6) and Gα_i3 antibodies (Calbiochem, n=8); (d) Gα_s antibodies (Calbiochem, n=6) and Gα_q/Gα₁₁ antibodies (NEN™, n=13). All antibodies were used at 1 : 200 v v⁻¹ dilution, except for Gα_i1/Gα_i2 and Gα_q/Gα₁₁ antibodies from NEN™ where 1 : 100 v v⁻¹ dilution was used. Each point indicates the mean±s.e.m. (vertical bars). The individual sets of points were fitted by the Hill equation (see Methods) with the parameters shown in Table 2. Significant difference in the group mean from the control mean value occurred only for Gα_i3/Gα_o and Gα_o antibodies (Table 3).